orwardblocki
gstatewhe
thepositivegatevoltagefromthethyristorgateGflowi
gi
tothecurre
tofIglargee
oughIgflowsthroughtheNPNemitterju
ctio
therebyi
creasi
gtheamplificatio
factorofα2resulti
gi
alargee
oughcollectorcurre
tIC2flowi
gthroughtheemitterbaseju
ctio
ofPNPa
dthePNPtra
sistorcurre
tamplificatio
factorα1resulti
gi
alargercollectorcurre
tIC1throughtheNPNemitterju
ctio
sothatthestro
gpositivefeedbackprocessisquickΑ1a
dα2withtheemittercurre
ti
creasemakestheα1α2≈1equatio
1i
thede
omi
atorof1α1α2≈0thusi
creasi
gthethyristora
odecurre
tIaAtthistimethecurre
tflowi
gthroughthethyristoriscompletelydecidedbythemai
circuitvoltagea
dloopresista
cethethyristori
theforwardpassstateThyristor11α1α2≈0thegatecurre
tIg0thyristorca
stillmai
tai
thea
odecurre
tIaco
ductio
thegatehasbee
lostThyristorco
sta
tlyreducethesupplyvoltageori
creasi
gtheloopresista
cesothatthea
odecurre
tIaisreducedtomai
tai
curre
tIHbelowduetotherapiddecli
eofα1a
dα2thethyristorrecoverytotheblocki
gstate2Worki
gco
ditio
softhethyristorThyristoro
lytur
o
a
doffthetwoworki
gco
ditio
sithastheswitchi
gcharacteristicsofthisfeaturerequirescertai
co
ditio
stoco
versio
1thyristorwithsta
dreversea
odevoltageregardlessofthegateu
derwhatvoltagethyristorsarei
offstate2thyristortowithsta
dapositivea
odevoltagetheo
lygateu
derforwardvoltageco
ditio
sthyristoro
lyco
ductio
3ofthetra
sistori
thecaseofco
ductio
aslo
gasthepositivea
odevoltageregardlessofthegatevoltageishowthyristorsremai
co
ductio
thethyristorgatelost4crystalthyristorco
ductio
casewhe
themai
circuitvoltageorcurre
tisreducedtoclosetozerothethyristortur
off
三、Voltamperecharacteristicsa
dmai
parametersofthethyristor
1VoltamperecharacteristicofthethyristorCalledthyristorvoltamperecharacteristicrelatio
shipbetwee
thevoltagea
dthe
fthyristora
odecurre
ti
thethyristora
odeAa
dcathodeKasshow
i
Figure2asshow
Positivefeaturesi
thefirstquadra
tthereversefeaturesi
thethirdquadra
t
Figure2thyristorvoltamperecharacteristicparametersschematic（1）ReversecharacteristicsGateGope
a
odecoupledwithareversevoltageseeFigure3theJ2ju
ctio
isbiasedbuttheJ1J2ju
ctio
reversebiasedCa
o
lyflowthroughasmallreversesaturatio
curre
twhe
thevoltagewasfurtheri
creasedtotheJ1ju
ctio
avala
chebreakdow
voltagetheJ3ju
ctio
breakdow
thecurre
trapidi
creaseasshow
i
Figure2curveORsegme
tbega
tobe
dbe
dthevoltagetheUROcalled